More xenos in my book is good, no matter what. I hope they bring back Kroot Mercs for 40k. For 30k I'd just rather see major factions though so I'd like to see the Hrud incorporated to be that, rather than a smaller faction. Porting them to 40k would be an added bonus. It will be interesting to see what 8th ed does with things like night fighting, inulnerable saves, cover, and armor modifiers do. There are several possibilities on how you could potentially work their darkness/distortion effect depending on how things go.